The present invention is useful for opening obstructions in blood vessels, such as human arteries. Much attention has been devoted to the development of techniques and apparatus for opening arterial obstructions to replace the dangerous, costly and rarely permanent bypass procedure. The copending application describes a catheter with a unique cutting tip that provides a substantially unobstructed passageway into and through the catheter for cut material due to its shape and drive arrangement. In that application, a thin-walled cylindrical cutter is driven by means of a thin, flexible wire attached to the cutter wall. The resulting off center drive arrangement enables free flow of cut material through the cutter and into the hollow catheter tube. Suction may be applied to the catheter to assist in drawing the cut material into the tube. It will be appreciated that the catheter tube of that invention and of the present invention may be used as the inner of two concentric tubes wherein a saline solution, or the like, may be introduced to the site of the obstruction through the outer tube and removed via the inner tube.
When dealing with large blood vessels, such as the femoral artery, relatively rigid catheter structures may be utilized with some degree of success. However, when dealing with very small blood vessels or with vessels that include relatively sharp bends or turns, the catheter must be extremely flexible. In general, a thin guide wire is positioned by the surgeon next to an obstruction in a blood vessel and a catheter tube introduced over the guide wire. The guide wire may be removed before commencing blockage opening procedures. Various well-known fluoroscopy techniques may be utilized for assisting the positioning of the guide wire, the guiding of the catheter to the site of the obstruction and the operation of the obstruction opening device.
In accordance with one aspect of the invention, the need for a separate guide wire is eliminated. In accordance with another aspect of the invention, the cutter tip itself is flexible to permit it to follow the orientation of the obstructed vessel and to negotiate relatively sharp turns therein.